Bag suitable for packaging of fruit and vegetable products and means for its manufacture

ABSTRACT

A bag ( 100 ) for packaging fruit and vegetable products ( 2 ) having a casing ( 103 ) for housing the products to be packaged and at least one first band ( 104 ) and one second band ( 105 ), each arranged on the outer face of the casing so as to seal the casing, the first band ( 104 ) being joined to the casing only at its ends ( 104   a,    104   b ) forming a handle ( 106 ) and the second band ( 105 ) joined along the length thereof to the associated face of the casing, forming a stable bottom ( 105   c ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Divisional of application Ser. No. 15/643,699, filed Jul. 7,2017, claiming priority based on Spanish Patent Application No. U201630891 filed Jul. 8, 2016, and Spanish Patent Application No. U201730690 filed Jun. 9, 2017, the contents of all of which areincorporated herein by reference in their entirety.

TECHNICAL FIELD OF THE INVENTION

The invention relates to a bag particularly suitable for packaging fruitand vegetable products of the type that comprises a tubular casing madeof mesh sealed at its ends by means of the juxtaposition and mutualjoining of bands, with the interposition of the mesh casing, eacharranged externally on a face of the casing.

The invention also relates to a station for producing bags for amanufacturing and packaging machine of products in bags, particularlysuitable for producing the bag that is object of the invention.

BACKGROUND OF THE INVENTION

Through patent document ES 2122490 a mesh bag is known comprising atubular mesh casing having, longitudinally arranged and on the outerside, a handle of resistant synthetic material welded at its ends to theends of said tubular casing coinciding with the weldings themselves forsealing of the casing.

To assist in sealing the casing, it comprises pieces of plastic bandlocated on the ends and outside the tubular mesh, opposite the ends ofthe strap that acts as a handle, such that the sealing of said casing issought by juxtaposing and mutually joining the ends of the handle andthese pieces of band with interposition of the mesh forming the casingat each end of said casing.

In some cases when gripping the bag by the handle or when handling thebags during storage or transport, the weight of the products housed inthe casing can cause a twisting effect therein such that it can preventthe bag from being exposed in a satisfactory way or that carrying it maynot be as comfortable as expected even though the bag has a handle.

Similarly, when the bag is gripped by the handle, the mesh material mustsupport the entire weight of the product housed inside, so that thethickness and size of the mesh must be selected correctly ensuring thatit will hold without breaking. Furthermore, the joint between the endsof the strap forming the handle and the tubular mesh must be carried outsuch as to ensure that said joint will withstand or resist the weight ofthe products. All of the foregoing means that certain features of thebag must be excessively oversized.

A known type of machine for manufacturing mesh bags based on the supplyof a continuous tubular mesh is one which comprises a station forproducing bags with an expansion device or expander core, arranged infloating and vertical manner on the inside of the tubular mesh andsupported by at least one pair of rotating rollers outside the mesh, theshafts of which are integral with the machine.

This expansion device is configured to cooperate with welding groupsarranged one on each side of the expansion device, and which, whenactuated, ensure the joining of the expanded tubular mesh as it passesthrough the expansion device and a sheet material which is placedoutside the tubular mesh.

Conventionally, the station for producing bags is further equipped witha sealing device of the tubular mesh, gathering and joining together thewall thereof through thermo welding or by other means. Usually, thesealing of the tubular mesh is made to coincide with a portion of thetubular mesh having sheet material attached, on one or both sidesthereof, in order to reinforce the sealing and prevent tearing of themesh at this point. Also conventionally, the station for producing bagsis equipped with a cutting device, downside of the sealing device, whichtransversally cuts the mesh immediately below the sealing area in orderto individualize a bag of continuous mesh, bag that remains open at thetop but closed at the bottom through previous actuation of the sealingdevice.

An example of a station for producing bags having these characteristicsis described in patent document ES2188389.

The individualized bag is transferred to other stations of the machine,where it will be filled and subsequently sealed by gathering and joiningtogether the walls of the bag in the vicinity of its upper opening.

The type of bags to be produced may vary according to whether the sheetmaterial is applied only on one side or on both sides of the tubularmesh, in the station for producing bags. Similarly, different bags canalso be produced depending on whether the sheet material is joined tothe body of the mesh along the entire length of a bag or only coincidingwith the bottom thereof and the upper opening.

Each of these alternatives requires the use of different welding groups.To that end, in order for a station for producing bags to besufficiently versatile and capable of making different types of bags, itis possible to equip the station for producing bags with an upperwelding group and a lower welding group, of a different typology, andenable the station for producing bags so that the expansion device canbe easily replaced, according to whether the latter should cooperatewith the upper welding group in order to manufacture a version of thebags, or with the lower welding group in order to manufacture otherversions of the bags.

In some cases, the bags, such as those that are object of the presentinvention, do not necessarily have to be symmetrical, that is, therelationship between the laminar sheet and the tubular mesh may bedifferent on either side of the tubular mesh. Thus, bags withinteresting added benefits can be obtained.

The production of these versions of the bags in a station for producingbags as described above is not well resolved because it requires the useof an upper welding group arranged on one side of the tubular mesh and alower welding group arranged on the opposite side of the tubular mesh,requiring the simultaneous use of two expansion devices when the stationis only able to support one of these at a time.

The first objective of the invention is a station for producing bagscapable of overcoming this drawback.

It is also an objective of the invention to maintain the production rateof the station for producing bags even when the bag being produced is ofthe type that requires operating with both welding groups at differentlevels.

DESCRIPTION OF THE INVENTION

The bag, object of the invention, replaces the pieces of band whichcharacterize the bag according to ES 2122490 by a continuous band thatlinks the two ends of the casing, this band being further joined alongits length to the associated face of the casing, forming a stable bagbottom for the contents of the casing when the bag is held suspendedfrom the handle. This bag bottom, besides contributing to hold theweight of the products endows the bag with a stability that is ofinterest for its use and that is favorable for the good performance ofthe bag.

Thus, the bag of the invention is a breathable bag especially suitablefor packaging fruit and vegetable products comprising a tubular meshcasing, capable of housing the products to be packaged, and at least onefirst band and one second band each arranged on the outer face of thecasing and joined together at their ends, with the interposition of endsof the casing, such that they seal said tubular casing. The bag ischaracterized in that the first band is joined to the casing only at itsends such that a central portion thereof is able to be separated fromthe casing forming a handle; the second band is joined along its lengthto the associated face of the casing, forming a stable bottom for thecontents of the casing when the bag is held suspended from the handle.

In the context of the present invention, tubular mesh should beunderstood as a mesh obtained in tubular fashion, or an originally flatmesh whose opposing side edges gathered and joined together form a tube.Similarly, the mesh may be an extruded mesh or a woven mesh withoutthese versions affecting the essence of the invention.

The second band may be joined to the associated face of the casing incontinuous or intermittent fashion, ensuring in any case that thissecond band cannot be separated and slid transversally with respect tothe casing, remaining stuck thereto.

Preferably, the second band is joined to the associated face of thecasing by two longitudinal joining strips, arranged at or near itslongitudinal edges.

The second band can provide the bag with a generous bottom, on which theproducts accumulate. Thus, the invention contemplates that the secondband be a band having parallel longitudinal edges that determine abandwidth h whose ratio to the perimeter l of the tubular casing ish/l≥0.2.

In a variant of the invention, said first and second bands are flattenedand have similar widths at their ends of mutual joining withinterposition of the mesh. Twisting of the casing is prevented when theaforementioned proportions are respected.

According to a variant of interest, the central portion of the firstband has a width that is significantly smaller than the width of thejoining ends thereof, with interposition of the mesh, with the secondstrip, such that it ensures good joining and prevents the casing fromtwisting, while at the same time it provides the handle with anergonomic grip portion.

Preferably, both first and second bands are made of a plastic materialsuitable for their mutual joining through thermo welding.

The inventors also propose a station for producing bags particularlysuited to producing the bag, which is the object of the invention.

The station is of the type comprising an expansion device made offlexible tubular material, from which the tubular casing of the bags isobtained, is intended to remain inserted vertically and floating insidesaid tubular material while producing the bags, and for which thestation is equipped with means of support on which the mentionedexpansion device rests, although with the interposition of tubularmaterial supplied while producing the bags and, if applicable, also ofsheet material, for example in the shape of a band or bands.

In essence, this station is characterized in that the expansion devicecomprises an upper expansion body, intended to cooperate with at leastone upper welding group for joining the expanded tubular material, as itpasses through this upper expansion body, with the sheet materialarranged between said tubular material and the upper welding group; anda lower expansion body, intended to cooperate with at least one lowerwelding group for joining the expanded tubular material, at it passesthrough this lower expansion body, with the sheet material arrangedbetween said tubular material and the lower welding group, the upper andlower expansion groups being mechanically linked to one another withcapacity of movement respect to each other.

The expansion device thus provides support surfaces at different levelsfor cooperating with welding groups that may be different and arrangedat different levels, which increases the versatility of the station forproducing bags making it capable of producing several different types ofbags, naturally including the bag that is object of the presentinvention.

Furthermore, the partition of the expansion device into two bodies,though linked mechanically, enables implementing the invention in asimple way without altering or having to modify the means of supportbeing used in a conventional manner. In other words, it is not necessaryto use means of support at a different level, each suitable forreceiving the support of a different expansion device.

The capacity for movement between the two expansion bodies, the upperexpansion body and the lower expansion body, of the expansion devicefurther enables actuation of the welding groups on the expansion device,at different levels, without impairing the precision of the operations,since it allows a certain automatic accommodation of each expansion bodywhen requested by the welding plates of the welding groups at theirlevel during their actuation.

The mechanical link between the upper and lower expansion bodies can bein the form of an articulated joint. In one embodiment, the upper andlower expansion bodies are joined in an articulated manner around atransversal shaft, which becomes horizontal when the expansion devicerests on the means of support.

According to a variant of the invention, the expansion device rests onthe means of support through support of the upper expansion body on saidmeans of support, with the lower expansion body being suspended from theupper expansion body.

To that end, the expansion device may be equipped with a pair ofrotating rollers around parallel rotating shafts, at a same level,positioned at the lower end of the upper support body.

The arrangement of these rotating rollers in the upper expansion bodymay be such that the upper end of the lower expansion body is arrangedtherebetween.

In one embodiment of the station, by resting the expansion device on themeans of support, the upper expansion body offers one first and onesecond opposing upper support faces, each of which can used for supporttubular material and sheet material for joining, and against which, inthis case, the welding plates of the corresponding first and secondupper welding groups actuate, arranged at the same level and betweenwhich the upper expansion body is located; and the lower expansion bodyoffers one first and one second opposing lower support faces, each ofwhich can be used for support tubular material and sheet material forjoining, and against which, in this case, the welding plates of thecorresponding first and second lower welding groups actuate, arranged atthe same level and between which the lower expansion body is located,the station for producing bags being prepared to both actuate or toactuate and operate said welding groups individually, simultaneously orcoordinately.

In an embodiment of interest, the station is capable of operating asingle upper welding group, on one side (L) of the expansion device anda single lower welding group, which is arranged on the other side (R) ofthe expansion device, and in addition, it is capable of doing sosimultaneously.

By operating it is understood that in addition to actuating the weldingplates associated to the welding group, moving them towards theexpansion device, supplying heat thereto so as to be able to jointubular material and sheet material by thermo welding, said materialhaving been arranged between said welding plates and the expansiondevice. This particular form of action is of interest for producing thebag object of the present invention.

According to a constructive solution, the lower expansion body comprisestwo parallel plates that determine two major opposing faces in the lowerexpansion body, each suitable for cooperating with a lower weldinggroup, said plates being joined to one another, freeing the space thatseparates them along the entire length of at least their lateral edges,thus determining vertical slots that enable the formation of individualfolds in the tubular material that surrounds it while the bags are beingproduced.

In a variant, said plates have a window in which a cover is placed, theouter surface of which is a covering material that provides non-stickproperties and high resistance to heat. This covering material may bemade of polytetrafluoroethylene (PTFE).

According to a constructive solution, the upper expansion body comprisesa rigid support frame for two pairs of welding backs, each pair ofwelding backs determining a larger face in the upper extension bodysuitable for cooperating with the associated welding group.

In a variant of interest, the welding backs of a same pair are mountedin a rotating way around a common shaft transverse to the upperexpansion body and which is essentially horizontal when the expansiondevice rests on the means of support. This enables the welding backs tobe better accommodated to the welding plates of the upper weldinggroups.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 illustrate schematically and from different points of viewa bag according to the invention in a rest position;

FIG. 3 would show the shape that the same bag adopts during transportwhen suspended from the handle;

FIG. 4 shows a station for producing the bag according to a variant ofthe invention;

FIG. 5 is a side elevation view of the station shown in FIG. 1 havingschematically added the supply of tubular material and the two bands ofsheet material from which an open bag can be produced, for example, ofthe type shown in FIGS. 1 to 3;

FIG. 6 is a front elevation view of the station shown in FIG. 4 havingdeprived the lower expansion body of one of the support faces thereoffor the tubular material and the sheet material so as to be able to showthe relationship thereof with an introducer penetrating into said lowerexpansion body;

FIG. 7 shows a side elevation of an expansion device of a stationaccording to the invention;

FIG. 8 shows the same expansion device according to cutting plane AA ofFIG. 8;

FIG. 9 shows an enlarged view of the area delimited and indicated withlegend B in FIG. 8; and

FIGS. 10 and 11 show how the position of the lower expansion body can bevaried with respect to the upper expansion body in an expansion deviceof a station according to the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT

The bag 100 illustrated by way of example in FIGS. 1 and 2 comprises atubular mesh casing 103 selected from the cross-sectional type of acontinuous tube, the ends 103 a and 103 b of which are closed betweenone first and one second band 104 and 105 of sheet material, such asthermo-weldable plastic, which are joined to one another by theiropposing ends 104 a, 105 a and 104 b, 105 b interposing the respectiveends 103 a and 103 b of the casing 103 by means of joints 108 extendingtransverse to the bands 104 and 105.

In the bag 100, the first band 104 has a central portion 104 c that isnot joined or otherwise attached in any way to the associated face ofthe casing 103. With the bag 100 resting on a surface, for example, ofexposure (as illustrated in FIG. 1), the first band 104 is naturallypositioned smoothly on said face of the casing 103. To this effect, alength is selected for the band 104 similar to the length of the casing103.

The mentioned central portion 104 c of the first band 104 is sized toact as a handle 106, being able to hold and carry the bag 100 gripped bythe handle 106.

In these circumstances, the casing 103 will assume a U-shape but in acontrolled or assisted manner, in this case through the second band 105.To this end, this second band 105, unlike the first band 104, is joinedto the associated face of the casing along its length preventing it frombeing able to separate therefrom, forming a bag bottom 105 c (see FIG.2) of the bag 100 when it is carried suspended from the handle 106.

This can occur even when the fist and second bands 104 and 105 are ofthe same length, which is very advantageous so as not to alter the usualproduction systems. By adopting the U-shape, the ends of the bag 100 arebrought close together, and as a result, the ends 104 a and 104 b of thefirst band 104 are also brought together, which allows the centralportion 104 c that acts as a handle 106 to separate from the casing 103.

It is of interest that the width of the second band 105 be sufficient inorder to provide the bag 100 with optimum stability during transport orto prevent unwanted twisting of the casing 103. To this effect, in a bag100 having capacity for 6 to 15 pieces of fruit (common format in themarketing of citrus fruit, apples, etc.) it would be desirable to selecta band with a width of between 90 and 160 mm as second band 105, with alength that can range between 20 and 40 cm, depending on the number ofpieces to be housed in the casing 103.

In practice, the perimeter of the tubular casing 103 for this type ofbag, intended to contain fruit and vegetable products, generally rangesfrom 400 to 600 mm, which means that by taking into account theabove-mentioned widths, in a small bag an optimum perimeter/width ratiocould be 400/90, which means a coverage of the second band 105 of about40% of the web casing in the example; and in the case of a large bag, anoptimum perimeter/width ratio could be 600/160, which means a coverageof about 25% of the casing 103.

In the example, the second band 105 is a straight band, in which twolateral edges are distinguished and along which, or in the vicinitywhereof, there are longitudinal joining strips 107 of this band to thecasing 103. The longitudinal strips may be continuous, but it is alsocontemplated that the joining points with the casing 103 be discreet,intermittent and having another distribution, but inasmuch as possible,ensuring that the second band 105 cannot be moved transverse to thecasing 103 and is secured thereto over its entire length so as to beable to carry out the function of a bottom of the bag 100 particularlywhen it is carried suspended from the handle 106, as illustrated in FIG.3.

In the example, in the areas of mutual joining the ends 103 a, 104 a and103 b, 104 b of the first and second bands 104 and 105 are flattened andare of the same or similar width and the joining is carried out bymelting (for example, by means of ultrasound or through the supply ofheat) the materials that form the bands 104 and 105 or by other meanssuch as stapling, gluing, sewing, etc. Conventionally, as describedabove, the joining areas may extend transversally to the bands 104 and105.

It should be noted that the first band 104 has a slight narrowing in itscentral portion 104 c, which favors comfortable fastening thereof whenit acts as a handle 106.

FIG. 4 shows a station 1 for producing open bags for a machine formanufacturing and packaging products in bags based on the supply offlexible tubular material, such as a woven mesh or a plastic mesh, andof a flexible sheet material in the form of a band or bands.

In a known manner, the station 1 comprises an expansion device 4, orexpander core, capable of being arranged in floating position orvertically inside the tubular material when it is supplied to producebags. For this purpose, the station is equipped with a means of support5 of the expansion device 4, in the example in the form of two rotatingrollers, the shafts of which are supported on a fixed, not shown,component of the station 1.

The expansion device 4 is configured to cooperate with the weldinggroups capable of procuring the joining of the expanded tubular materialwith the sheet material as it passes through the expansion device,arranged between said tubular material and the welding groups.

The station 1 of FIG. 4 is particular in that the expansion device 4comprises an upper expansion body 4 a and a lower expansion body 4 bjoined in an articulated manner around a transverse shaft 6 that isessentially horizontal when the expansion device 4 is supported on themeans of support 5. In the example, the expansion device 4 is supportedon the means of support 5 by the lower part of the upper expansion body4 a, the lower expansion body 4 b being suspended.

In order to allow feeding of the tubular material between the upperexpansion body 4 a and the means of support 5, said upper expansion body4 a mounts rotating rollers 13 around rotation shafts 13 a (see FIG. 6)parallel and at the same level, each of which rests on one of therotating rollers of the means of support 5.

The upper expansion body 4 a is meant to cooperate with a least oneupper welding group, and the lower expansion body 4 b is meant tocooperate with at least one lower welding group.

In the station 1 of the example, the upper expansion body 4 a has onefirst and one second support faces 14, 15 which are opposite one another(see FIG. 5), each of which can be used to support the tubular materialand the sheet material to be joined and against which, in this case, thewelding plates 16, 17 of a first and second upper welding groups 18, 19can actuate, arranged at the same level and between which the upperexpansion body 4 a is located, all of which can better be appreciated inFIG. 5.

In turn, the lower expansion body 4 b also offers one first and onesecond support faces 20, 21 opposite one another, each of which can beused to support the tubular material 2 and the sheet material to bejoined and against which, in this case, the welding plates 22, 23 ofcorresponding first and second lower welding groups 24, 25 can actuate,arranged at the same level and between which the lower expansion body 4b is located.

The station 1 is prepared both to actuate or to actuate and operate thedifferent welding groups individually, simultaneously or coordinately.As it has been clarified previously, by operating it is understood thatin addition to displacing the welding plates associated to the weldinggroup, heat is supplied thereto so as to be able to join tubularmaterial and sheet material by thermo welding, said material having beenarranged between said welding plates and the expansion device.

The configuration of the welding plates of the upper and lower weldinggroups being different, the station 1 allows producing several differenttypes of bags depending on the combination of welding groups operatingon the tubular material and the sheet material to be joined together.

The station 1 is particularly advantageous when being actuated andoperated simultaneously on the expansion device 4 with several weldinggroups, of which at least one is the upper welding group and another isthe lower welding group.

One example is shown schematically in FIG. 5, suitable for producing abag 100 as shown in FIGS. 1 to 3. A particular feature of this bag isthat the casing 103 can be obtained from a tubular material 2, in theform of woven or plastic mesh, and two bands 104 and 105 of sheetmaterial, each one applied to one side of the tubular material 2 andjoined thereto in a different manner: in one case joined along thelength of the tubular material 2 forming the casing 103; and in theother case, joined only to the ends of the casing 103. In the example ofFIGS. 1 to 3, the bands 104 and 105 of sheet material also havedifferent shapes.

One form for the mass production of this type of bag by means of astation 1 like that of FIGS. 4 to 6 involves supplying the tubularmaterial 2 and the two bands 104, 105 as illustrated in FIG. 5 andsimultaneously actuating the welding plates 16, 17 of the first andsecond upper welding groups 18, 19 against the first and second uppersupport faces 14, 15 of the upper expansion body 4 a, respectively, butoperating only with one of the upper welding groups by supplying heatonly to the plates of one of these upper welding groups, for example tothe plates 16 arranged on a first side L of the expansion device 4; andactuating the welding plates 22 and 23 of the two lower welding groups24, 25 against the first and second lower support faces 20, 21 of thelower expansion body 4 b, but operating only with one of these lowerwelding groups, supplying heat only to the plate 23 of the weldinggroups arranged on the side R opposite to the expansion device 4. Thus,in a same working cycle of the station 1, the sheet material 105 isjoined along the length of a section of the tubular material 2 formingthe casing 103 of a bag in the process of being manufactured on the Lside of the expansion device 4; and the sheet material 104 is joined toone of the ends of a section of the tubular material 2 forming thecasing of another bag in the course of manufacturing, which precedes theprevious bag and onto which the sheet material 105 has already beenjoined along the length thereof, on the side R of the expansion device.

In addition to the station 1 providing support surfaces at differentlevels in order to cooperate with different welding groups arranged at adifferent level, the articulated joint between the upper and lowerexpansion bodies 4 a and 4 b makes it possible that the mechanicalthrust that may be exerted by the upper welding groups on the supportsurfaces at its level does not result in a displacement of the lowerlever support surfaces causing an undesired mismatch with the associatedlower welding groups.

An example of an expansion device 4 with an articulated joint betweenthe upper and lower expansion bodies 4 a y 4 b is exemplified in FIGS. 7to 9, and its effect is illustrated in FIGS. 10 and 11.

FIGS. 7, 8 and 9 show that the upper end of the lower expansion body 4 bis arranged between the two rotating rollers 13 of the upper expansionbody 4 a intended to rest, in rotating mode, on the means of support 5of the station 1. As illustrated in FIGS. 10 and 11, this circumstancedoes not prevent the rotation of the lower expansion body 4 b withrespect to the upper expansion body 4 a to a sufficient extent so thateach of these upper and lower bodies 4 a and 4 b can be properly alignedwith the welding plates of the upper and lower welding groups operatingat their level.

In the example of these FIGS. 7, 8 and 9, the upper expansion body 4 acomprises a rigid support frame 11 for two pairs of welding backs 12,each pair of welding backs determining one of the support faces 14, 15in the upper expansion body 4 a suitable for cooperating with thewelding plates 17, 18 of the first and second upper welding groups 18and 19, respectively.

The welding backs 12 of a same pair are furthermore mounted in arotating way around a common shaft 12 a, transverse to the upperexpansion body 4 a, which is essentially horizontal when the expansiondevice 4 rests on the means of support 5, which also contributes to abetter accommodation of the welding plates 17 and 18.

As regards the lower expansion body 4 b, in the example it comprises twoparallel plates 35, 36, which determine the support faces 20 and 21 inthe lower expansion body 4 b, opposed to one another, each suitable forcooperating with the plate 22, 23 of a respective lower welding group 24and 25.

The plates 35 and 36 are joined together freeing the space thatseparates them along the entire length of at least their lateral edges,thus determining vertical slots 27 that enable the formation ofindividual folds in the tubular material 2 that wraps around them duringproduction of the bags.

In FIG. 6, in which the lower expansion body 4 b has been deprived ofone of its plates, an introducer 37 is shown comprising two fingers 37a, which penetrate through the vertical slots 27 from the outside intothe lower expansion body 4 b, gradually, in the forward direction of thetubular material during the production process of the bags. Thisintroducer 37 enables the tubular material to be folded inwardly,preparing it for the transverse welding that will form the closed bottomof the bag.

FIGS. 4 to 6 show schematically a sealing and cutting device 39, whichproduces the bottom of the bags. This sealing and cutting device 39 isin itself known and is not described in greater detail because it is notan essential part of the invention.

A preferred characteristic of the plates 35 and 36 is shown in FIG. 4.Specifically, the plates 35 and 36 have a window into which a cover 28and 29, respectively, is placed, the outer surface of which is acovering material that provides non-stick properties, highly resistantto heat, suitable for serving as a welding back for the welding plates22 and 23. This covering material may be made of, for example,polytetrafluoroethylene (PTFE).

The invention claimed is:
 1. A breathable bag for packaging fruit andvegetable products comprising a tubular mesh casing configured to housethe products to be packaged, and at least one first band and one secondband each arranged on a respective outer face of the casing and joinedtogether at respective ends of the first band and the second bandinterposed with respective ends of the casing, so as to seal saidcasing, wherein the first band is joined to the casing only at the endsof the first band such that a central portion thereof is configured tobe separated from a body of the casing forming a handle, and wherein thesecond band is joined to the associated respective face of the casing atmultiple locations along a longitudinal length of the casing extendingbetween the ends of the casing, forming a stable bag having a U-shapedbottom for contents of the casing when the bag is suspended from thehandle; and wherein the second band is a band having parallellongitudinal edges that determine a band width h whose ratio to aperimeter 1 of the tubular casing is h/l≥0.2.
 2. The bag according toclaim 1 wherein the second band is joined to the associated face of thecasing in a continuous fashion.
 3. The bag according to claim 2 whereinthe second band is joined to associated face of the casing by twolongitudinal joining strips arranged at or near to the longitudinaledges of said second band.
 4. The bag according to claim 1, wherein attheir ends of mutual joining with interposition of the casing, thementioned first and second bands are flattened and have similar widths.5. The bag according to claim 4, wherein the central portion of thefirst band has a width that is significantly smaller than the width ofthe joining ends thereof, with interposition of the casing, with thesecond band.
 6. The bag according to claim 1, wherein the least onefirst band and the one second band are joined together so as to formcontinuous bands at the respective ends without openings for manualgripping.